Wireless communication systems are widely deployed to provide various types of communication content such as voice and data. Typical wireless communication systems may be multiple-access systems capable of supporting communications with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, such systems can conform to specifications such as those of third generation partnership project (3GPP), third generation partnership project 2 (3GPP2), 3GPP long-term evolution (LTE), LTE Advanced (LTE-A), etc.
Wireless communication systems, such as cellular communication systems, allow a user equipment (UE) to communicate wirelessly by establishing a wireless (e.g., radio) link between the user equipment and one of a number of available base stations (BS) or cells which are geographically distributed throughout a service area. User equipment, as used herein, is a broad term and can refer to a single device or multiple devices. Mobility is provided by means of protocols that enable the user equipment to be handed off from a first base station to a second base station as it moves from a coverage area of the first base station to another coverage area of the second base station. Various base stations may be connected (e.g., by means of wireless and/or wired links) to a public land mobile network (PLMN), which provides a necessary infrastructure for servicing calls. A PLMN typically has connections to public switched telephone networks (PSTNs) to enable calls to be routed to wire-line communication devices that are not associated with a PLMN.
Wideband code division multiple access (WCDMA) systems of 3GPP are wideband CDMA mobile communication systems operating over a 5 MHz channel with a channel raster of 200 KHz. There are multiple communication bands, such as International Mobile Telecommunications-2000 (IMT-2000) bands and Personal Communications Service (PCS) bands, supporting WCDMA systems and each spanning a 60 MHz bandwidth on downlinks.
Generally, wireless multiple-access communication systems may simultaneously support communications for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations.
When power is supplied to a user equipment, the user equipment performs a downlink synchronization of a base station and acquires a primary scrambling code (PSC) of the base station. Such a process is generally referred to as a cell search. The cell search is a procedure by which a user equipment acquires time and frequency synchronization with a base station and detects cell identities of the base station. In general, a cell search may be classified into an initial cell search, which is initially performed when a user equipment (UE) is powered on, or a target cell search which performs a handover or a neighbor cell measurement When the UE moves from cell to cell.
A user equipment consumes a relatively large amount of power consumption performing cell searches. When a user equipment starts a cell search procedure, it will identify at least a WCDMA channel, determine slot boundaries, determine frame boundaries, identify at least a PSC of a base station and finally identify a cell before starting communication with the base station. Because a user equipment may be powered on essentially anywhere and accuracy of a user equipment's oscillator can also vary, an initial cell search may involve searching for control channels of cells throughout an entire available radiofrequency band. For example, a base station search can identify one or more base stations having the best signal characteristics for communication with the user equipment, but this also can be a power consuming task. Accordingly, improved methods and devices for determining communication information for wireless mobile devices are desired.